11-16-03 20:50
No 471245
All the experimental procedures I have seen for the production of 1-(2,5-dimethoxyphenyl)-2-nitroethane describe the product as a yellow oil.
Is it possible to crystallize this oil from absolute ethanol?
Two samples of this compound that were produced according to Barium's EtOAc/ethanol method to be found at:
../rhodium /nitrost
One of these samples smelt somewhat of acetic acid at the end of the procedure, and was therefore washed with dH2O (the oil was washed directly with dH2O and was not then extracted with organic solvent, dried and evaporated). It can be assumed that this sample therefore contained some water.
This sample, and another, were both dissolved in separate portions of boiling absolute ethanol.
On cooling, the wet sample has formed some white crystals and the remaining mother liquor is bright yellow. Further cooling of this solution causes a yellow goo to fall out of solution around the white crystals.
The other sample (the dry one) fails to form crystals on cooling even when seeded with one of the white crystals from the wet sample recrystallization.
Can anyone enlighten me as to the mp. of 1-(2,5-dimethoxyphenyl)-2-nitroethane please?
Are the white crystals that have fallen out of the first sample likely to be 1-(2,5-dimethoxyphenyl)-2-nitroethane or something else (e.g. ketone from an undesired nef reaction)?
Has anyone here ever recrystallized 1-(2,5-dimethoxyphenyl)-2-nitroethane and if so, from what solvents/ratios?
Many thanks for your help.
(Chief Bee)
11-16-03 23:52
No 471272
The substance is very likely an oil at room temperature, and it will not crystallize unless cooled to low temperatures.
Here below are two references to the synthesis of 1-(2,5-dimethoxyphenyl)-2-nitropropane, and its boiling point is given as 135-140°C/0.1 mmHg and it is a liquid at room temp. The nitroethane should have similar properties, but it is not reported in the literature.
Org. Prep. Proced. 2, 25 (1970) [CA 72, 90607s (1970)]
Can. J. Chem. 49, 3143-3151 (1971)
(Stranger)
11-24-03 04:47
No 472773
Starlight,
I obtained a similar product after recrystallizing a brown post BH4 reaction goo with methanol. White crystals, along with a certain amount of yellow fine precipitate caused by shaking the brown goo with water. Recently reduced the white material with aluminum amalgam in straight methanol but am waiting to work it up. Will keep you posted.
P.S. Can someone talk about the physical characteristics of 2CH freebase? I obtained a minute amount of yellowish/golden oil coating the inside of flask. Smelled very peculiar and definitive, can't quite describe it. Tasted very bitter and numbing. This was at 200C+ and ice water vac on microscale from a LAH reduction.
(Chief Bee)
11-24-03 10:47
No 472840
2C-H is a moderately viscous clear (water-white) oil when pure, with a characteristic amine smell. Its boiling point is 120-130°C @ 0.5 mmHg and 80-100°C @ 0.4 mmHg according to Pihkal. The free base rapidly picks up carbon dioxide when exposed to the air, forming a white, hard carbonate salt.